docs: def T_stagnation(T, P, Pst, k):
      r'''Calculates stagnation flow temperature `Tst` for a fluid with the
      given isentropic coefficient and specified stagnation pressure and
      normal pressure. Normally used with converging/diverging nozzles.
  
      .. math::
          T=T_0\left(\frac{P}{P_0}\right)^{\frac{k-1}{k}}
  
      Parameters
      ----------
      T : float
          Normal temperature of a fluid [K]
      P : float
          Normal pressure of a fluid [Pa]
      Pst : float
          Stagnation pressure of a fluid moving at a certain velocity [Pa]
      k : float
          Isentropic coefficient []
  
      Returns
      -------
      Tst : float
          Stagnation temperature of a fluid moving at a certain velocity [K]
  
      Notes
      -----
      Assumes isentropic flow.
  
      Examples
      --------
      Example 12-1 in [1]_.
  
      >>> T_stagnation(286.8, 54050, 54050*8, 1.4)
      519.5230938217768
  
      References
      ----------
      .. [1] Cengel, Yunus, and John Cimbala. Fluid Mechanics: Fundamentals and
         Applications. Boston: McGraw Hill Higher Education, 2006.
      '''
      return T*(Pst/P)**((k - 1.0)/k)